# APPENDIX 5-D. ROOM AIR CONDITIONER ENGINEERING DATA

TABLE OF CONTENTS

5-D.1 INTRODUCTION ..................................................................................................... 5-D-1

5-D.2 MANUFACTURING COST MODELING DETAILS........................................... 5-D-1

5-D.3 ENERGY MODELING DETAILS .......................................................................... 5-D-9

5-D.4 DESCRIPTION OF SUPPORTING ANALYSES................................................ 5-D-16

5-D.4.1 Room Air Conditioner Airflow Modeling.............................................................. 5-D-16

5-D.4.2 Room Air Conditioner Motor Analysis .................................................................. 5-D-17

LIST OF TABLES

Table 5-D.2.1 Incremental Cost Detail for 5,200 Btu/h Louvered, No Reverse Cycle

Room Air Conditioner (Product Class 1)..................................................... 5-D-2

Table 5-D.2.2 Incremental Cost Detail for 8,000 Btu/h Louvered, No Reverse Cycle

Room Air Conditioner (Product Class 3)..................................................... 5-D-4

Table 5-D.2.3 Incremental Cost Detail for 12000 Btu/h Louvered, No Reverse Cycle

Room Air Conditioner (Product Class 3)..................................................... 5-D-5

Table 5-D.2.4 Incremental Cost Detail for 24000 Btu/h Louvered, No Reverse Cycle

Room Air Conditioner (Product Class 5)..................................................... 5-D-6

Table 5-D.2.5 Incremental Cost Detail for 8000 Btu/h Non-Louvered, No Reverse

Cycle Room Air Conditioner (Product Class 8).......................................... 5-D-7

Table 5-D.2.6 Incremental Cost Detail for 12000 Btu/h Non-Louvered, No Reverse

Cycle Room Air Conditioner (Product Class 8).......................................... 5-D-8

Table 5-D.3.1 MarkN Results for 5200 Btu/h Louvered, No Reverse Cycle Room Air

Conditioner (Product Class 1) .................................................................... 5-D-10

Table 5-D.3.2 MarkN Results for 8000 Btu/h Louvered, No Reverse Cycle Room Air

Conditioner (Product Class 3) .................................................................... 5-D-11

Table 5-D.3.3 MarkN Results for 12000 Btu/h Louvered, No Reverse Cycle Room

Air Conditioner (Product Class 3)..............................................................5-D-12

Table 5-D.3.4 MarkN Results for 24000 Btu/h Louvered, No Reverse Cycle Room

Air Conditioner (Product Class 5)..............................................................5-D-13

Table 5-D.3.5 MarkN Results for 8000 Btu/h Non-Louvered, No Reverse Cycle

Room Air Conditioner (Product Class 8)................................................... 5-D-14

Table 5-D.3.6 MarkN Results for 12000 Btu/h Non-Louvered, No Reverse Cycle

Room Air Conditioner (Product Class 8)................................................... 5-D-15

Table 5-D.4.1 Components Modeled to Calculate Room Air Conditioner Airflow ....... 5-D-17

5-D-i

# LIST OF FIGURES

Figure 5-D.4.1 Motor Incremental Cost Steps .................................................................... 5-D-18

Figure 5-D.4.2 Motor Shaft Output Ratings by Capacity for Different Product Classes.5-D-18

Figure 5-D.4.3 Motor Pricing Increase with Weight Increase ........................................... 5-D-20

Figure 5-D.4.4 Weight-Current Curves for room air conditioner PSC motors, grouped

by shaft output ............................................................................................. 5-D-21

Figure 5-D.4.5 Cost of Increased Efficiency for Different Motor Output Ratings........... 5-D-22

Figure 5-D.4.6 Brushless DC Motor Cost Curve by Shaft Output Rating ........................ 5-D-23

5-D-ii

# APPENDIX 5-D. ENGINEERING DATA

5-D.1 INTRODUCTION

Chapter 5 presents incremental cost curves describing costs to attain each analyzed

efficiency level for the six products analyzed in detail. The U.S. Department of Energy (DOE)

developed the curves using design option analysis based on energy use modeling using the

MarkN program and manufacturing cost modeling.

The tables in section 5-D.2 show the costs associated which each of the design

configurations analyzed. The tables identify the design options associated with each design

configuration and show the key elements comprising the cost impacts, including materials, labor,

overhead, and depreciation. The tables also present total manufacturing production cost (MPC),

total manufacturer sales price (MSP), and shipping cost associated with each design

configuration.

Details of the energy modeling are presented in section 5-D.3. Tables in this section

identify for each analyzed design configuration the MarkN input file name, the compressor data

file name, the MarkN key program output (energy efficiency ratio (EER) and capacity), standby

energy use, and integrated efficiency (integrated energy efficiency ratio (IEER)).

Details of two aspects of the engineering analysis are presented in section 5-D.4. Section

5-D.4.1 describes the airflow analysis that DOE used to account for changes in the airflow

system, including changes to fans and heat exchangers. Section 5-D.4.2 describes the data

collection and analysis used to develop the incremental cost estimates associated with increasing

motor efficiency, both with higher-efficiency permanent split capacitor (PSC) motors and with

brushless direct current (BLDC) motors.

5-D.2 MANUFACTURING COST MODELING DETAILS

The tables in this section itemize the results of the manufacturing cost analysis. The

tables identify for each of the analyzed products the analyzed design configurations and their

associated EER and IEER. The successive design configurations represent baseline designs with

increasing numbers of design options. The total and incremental costs associated with each of the

design configurations are presented in the tables as well, with separate identification of the key

cost elements: materials, labor, overhead, depreciation, and shipping cost. The incremental

manufacturing costs represent increases in MPC. The tables also show total MPC and MSC

calculated for each design configuration. Chapter 5 describes the conversion of this data into

incremental costs for specified efficiency levels (rather than by design configuration). The

efficiency level format of the data is used in the downstream analyses ( i.e. , life-cycle cost (LCC),

national impact analysis (NIA), etc.)

5-D-1Table 5-D.2.1Incremental Cost Detail for 5,200 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class1)DesignConfigurationDescriptionEERIEERIncremental Costs (MPC)Total CostMaterialLaborOHDepre­ciationIncreaseCumulativeIncreaseMPCMSP*ShippingHFC-22 Baseline9.79.52------$128.03$161.32$3.86R-410A Conversion8.948.79$3.92---$3.92$3.92$131.95$166.26$3.861 Add Subcooler9.189.02$0.57$0.25$0.10$0.02$0.94$4.86$132.89$167.44$3.862 Increase Evap Circuits9.379.20$0.75---$0.75$5.61$133.64$168.39$3.863 Increase Evap Width9.539.36$0.52$0.13$0.06$0.06$0.77$6.38$134.41$169.36$3.864 Increase Chassis toMedium Size10.5210.31$6.50$0.57$0.29$0.09$7.44$13.82$141.85$178.73$5.725 Stand-by Reduction10.5210.41$1.00---$1.00$14.82$142.85$179.99$5.726 Increase Chassis toLarge Size11.4911.37$20.08$2.46$1.11$0.97$24.62$32.00$160.03$201.64$5.727 Increase HXer TubeODs11.8311.70$4.31$0.65$0.26$0.09$5.30$37.30$165.33$208.32$8.398 Increase PSCEfficiency12.2012.06$8.11---$8.11$45.41$173.44$218.53$8.399 DC Brushless Motor12.3212.18$51.61---$51.61$88.91$216.94$273.34$8.39*MSP is equal to MPC times the manufacturer markup of 1.26.5-D-2Add subcooler with 0.25 inches (in) outer diameter (OD), 24.25 in. length, and condensate temperature of 95o F(1)Increase total refrigerant circuits in evaporator from 1 circuit to 2 circuits(2)Increase evaporator width by 2 in.(3)by redesigning the unit’s user interface placement.Increase Baseline Chassis Size by: Width 3 in., Height 0.75 in., Depth 2 in.(4)Change Main Control Board to a Switching Power Supply.(5)Increase Baseline Chassis Size by: Width 4.19 in., Height 1.88 in., Depth 5.72 in. Convert Condenser and Evaporator to 3-tube row heat exchangers(6)and change Condenser to Plain FinIncrease tubing OD in condenser and evaporator from 5millimeter (mm)(7)to 7 mmReplace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor(8)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(9)5-D-3Table 5-D.2.2Incremental Cost Detail for 8,000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class3)Design Option StepEERIEERIncremental CostsTotal CostMaterialLaborOHDepre­ciationIncreaseCumulativeIncreaseMPCMSPShippingR-410A Conversion8.799.19$5.47---$5.47$5.47$164.65$207.46$6.321 Increase EvapWidth9.199.43$0.79$0.19$0.09$0.04$1.12$6.59$165.77$208.87$6.322 Increase Evap TubeOD9.439.58$1.24$0.22$0.09$0.03$1.58$8.17$167.35$210.86$6.323 Add Subcooler9.589.68$0.85$0.36$0.14$0.06$1.41$9.58$168.76$212.64$6.324 Increase Chassis toMedium Size9.6810.56$11.36$0.76$0.36$0.44$12.92$22.50$181.68$228.92$6.325 Stand-by Reduction10.5610.63$1.00---$1.00$23.50$182.68$230.18$9.586 Increase Chassis toLarge Size10.6311.04$18.43$1.63$1.00$0.67$21.73$32.31$191.49$241.28$14.637 Increase PSCEfficiency11.0411.62$13.70---$13.70$46.01$205.19$258.54$14.638 DC Brushless Motor11.6211.81$76.84---$76.84$109.15$268.33$338.10$14.63Increase evaporator width by 3 in.(1)by redesigning the unit’s user interface placementIncrease tubing OD in evaporator from 5 mm to 7 mm(2)Add subcooler with 0.25 in. OD, 24.25 in. length,(3)and condensate temperature of 95o FIncrease baseline chassis size by: Width 0.81 in., Height 3.13 in., Depth 2.5 in.(4)Change Main Control Board to a Switching Power Supply.(5)Increase baseline chassis size by: Width 4 in., Height 2.75 in., Depth 8.1 in.(6)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(7)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(8)5-D-4Table 5-D.2.3Incremental Cost Detail for 12000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class3)Design Option StepEERIEERIncremental CostsTotal CostMaterialLaborOHDepre­ciationIncreaseCumulativeIncreaseMPCMSPShippingHFC-22 Baseline9.89.72------$206.92$260.72$13.92R-410A Conversion9.419.34$7.49---$7.49$7.49$214.41$270.16$13.921 Add Subcooler9.589.51$0.77$0.36$0.14$0.06$1.33$8.82$215.74$271.83$13.922 Increase Chassis Size toMedium Size10.8110.72$11.26$0.73$0.30$1.0613.36$22.18$229.10$288.67$16.933 Standby Reduction11.0710.76$1.00---$1.00$23.18$230.10$289.93$21.794 Increase Chassis Size toLarge Size11.0711.02$11.51$1.14$0.54$1.25$20.63$30.45$237.37$299.09$21.795 Increase Evap Tubes OD11.1411.09$2.57$0.38$0.15$0.06$3.16$33.61$240.53$303.07$21.796 Increase PSC Efficiency11.4811.43$14.68---$14.68$48.29$255.21$321.56$21.797 DC Brushless Motor11.5911.54$80.45---$80.45$114.06$320.98$404.43$21.79Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F(1)Increase baseline chassis size by: Width 1 in., Height 2.5 in., Depth 0 in.(2)Change Main Control Board to a Switching Power Supply.(3)Increase baseline chassis size by: Width 2.75 in., Height 2.5 in., Depth 4.5 in.(4)Increase tubing OD in evaporator from 5 mm to 7 mm(5)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(6)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(7)5-D-5Table 5-D.2.4Incremental Cost Detail for 24000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class5)Design Option StepEERIEERIncremental CostsTotal CostMaterialLaborOHDepre­ciationIncreaseCumulativeIncreaseMPCMSPShippingHFC-22 Baseline8.58.47------$301.21$379.53$23.10R-410A Conversion7.877.84$13.70---$13.70$13.70$314.91$396.79$23.101 Add Subcooler8.178.14$1.05$0.64$0.26$0.07$2.02$15.72$316.93$399.33$23.102 Increase Chassis sizeto Medium Size8.988.95$17.12$1.45$0.63$0.44$19.64$35.36$336.57$424.08$27.223 Increase Chassis sizeto Large size9.769.72$37.24$2.87$1.23$1.42$50.31$65.03$366.24$461.46$36.464 Standby Increase8.989.74$1.00---$1.00$66.03$367.24$462.72$36.465 Increase PSCEfficiency10.0610.04$44.25---$44.25$110.28$411.49$518.48$36.466 Scroll Compressor10.5510.53$175.00---$175.00$285.28$586.49$738.98$36.467 DC Brushless Motor10.6610.63$170.58---$170.58$411.61$712.82$898.15$36.46Add subcooler with 0.282 in OD, 63 in. length, and condensate temperature of 95o F(1)Increase baseline chassis size by: Width 1.75 in., Height 0.25 in., Depth 2.53 in.(2)Increase baseline chassis size by: Width 3.81 in., Height 4.69 in., Depth 2.53 in.(3)Change Main Control Board to a Switching Power Supply.(4)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(5)Replace Rotary Compressor with Scroll Compressor(6)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(7)5-D-6Table 5-D.2.5Incremental Cost Detail for 8000 Btu/h Non-Louvered, No Reverse Cycle Room Air Conditioner (ProductClass 8)Design Option StepEERIEERIncremental CostsTotal CostMaterialLaborOHDepre­ciationIncreaseCumulativeIncreaseMPCMSPShippingR-410A Conversion8.438.34$5.77---$5.77$5.77$216.23$ 272.44$12.261 Increase Evap Width9.449.34$4.69$0.26$0.12$0.00$5.08$10.85$221.31$ 278.85$12.262 Add Subcooler9.599.48$0.77$0.36$0.14$0.04$1.32$12.17$222.63$ 280.51$12.263 Stand by9.599.53$1.00---$1.00$13.17$223.63$ 281.77$12.264 Increase PSCEfficiency10.059.99$15.68---$14.68$27.85$238.31$ 300.27$12.265 Increase Evap TubeOD10.1710.11$3.21$0.50$0.22$0.04$3.97$31.82$242.28$ 305.27$12.266 DC Brushless Motor10.3310.26$80.45---$80.45$97.59$308.05$ 388.14$12.26Increa(1)se evaporator width by 4 inches by redesigning the unit’s user interface placement.Add subcooler with 0.25 in. OD, 24.25 in. length, and condensate temperature of 95o F(2)Change Main Control Board to a Switching Power Supply(3)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(4)Increase tubing OD in evaporator from 5 mm to 7 mm(5)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(6)5-D-7Table 5-D.2.6Incremental Cost Detail for 12000 Btu/h Non-Louvered, No Reverse Cycle Room Air Conditioner (ProductClass 8)Design Option StepEERIEERIncremental CostsTotal CostMaterialLaborOHDepre­ciationIncreaseCumulativeIncreaseMPCMSPShippingR-410A Conversion8.378.32$7.95---$7.95$7.95$237.28$298.97$12.261 Add Subcooler8.578.51$0.77$0.36$0.14$0.00$1.27$9.22$238.55$300.57$12.262 Increase Cond widthw/ Coil Bend8.878.80$1.93$0.34$0.16$0.00$2.43$11.65$240.98$303.63$12.263 Increase Evap width9.359.28$7.50$0.41$0.20$0.00$8.11$19.76$249.09$313.85$12.264 Increase Evap TubeOD9.559.48$3.44$0.45$0.18$0.00$4.06$23.82$253.15$318.97$12.265 Standby Increase9.559.51$1.00---$1.00$24.82$254.15$320.23$12.266 Increase Cond TubeOD9.689.64$3.95$0.30$0.12$0.00$4.38$29.20$258.53$325.75$12.267 Increase PSCEfficiency10.019.97$13.70---$13.70$42.90$272.23$343.01$12.268 DC Brushless Motor10.1110.07$76.93---$76.93$106.13$335.46$422.68$12.26Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F(1)Increase condenser width by 5 inches by bending the condenser coil to create more room.(2)Increase evaporator width by 6(3)inches by redesigning the unit’s user interface placement.Increase Tubing OD in Evaporator from 5 mm to 7 mm(4)Change Main Control Board to a Switching Power Supply(5)Increase tubing OD in condenser from 5 mm to 7 mm(6)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(7)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(8)5-D-8

# 5-D.3 ENERGY MODELING DETAILS

The tables in this section identify the analyzed design configurations for the analyzed

products. For each design configuration, the tables present the key MarkN outputs (capacity and

EER), the standby energy use, the IEER, and the MarkN input and compressor files used in the

analysis. The MarkN program, a MarkN user manual, and the input and compressor files will be

made available on the website for this rulemaking.

5-D-9Table 5-D.3.1MarkN Results for 5200 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class 1)Design ConfigurationDescriptionMarkN Input FilenameCompressor Map(EER, Capacity)MarkN OutputsStand-byPowerIEEREERCapacityHFC-22 BaselineIn_PC1_Baseline_R22.dat11.1 EER 5.2 kBtu/h9.7253751.49.55R-410A ConversionIn_PC1_Baseline_R410A.dat9.7 EER 4.6 kBtu/h8.9446241.48.791 Add SubcoolerIn_PC1_Step1.dat9.7 EER 4.6 kBtu/h9.1846891.49.022 Increase Evap CircuitsIn_PC1_Step2.dat9.7 EER 4.6 kBtu/h9.3748341.49.203 Increase Evap WidthIn_PC1_Step3.dat9.7 EER 4.6 kBtu/h9.5349271.49.364 Increase Chassis toMedium SizeIn_PC1_Step4.dat9.7 EER 4.6 kBtu/h10.5250611.410.315 Stand-by ReductionIn_PC1_Step5.dat9.7 EER 4.6 kBtu/h--0.710.416 Increase Chassis toLarge SizeIn_PC1_Step6.dat9.7 EER 4.6 kBtu/h11.4953540.711.377 Increase HXer Tube ODsIn_PC1_Step7.dat9.7 EER 4.6 kBtu/h11.8354020.711.708 Increase PSCEfficiencyIn_PC1_Step8.dat9.7 EER 4.6 kBtu/h12.2054040.712.069 DC Brushless MotorIn_PC1_Step9.dat9.7 EER 4.6 kBtu/h12.3254040.712.18Add subcooler with 0.25 in. outer diameter (OD), 24.25 in. length, and condensate temperature of 95o F(1)Increase total refrigerant circuits in evaporator from 1 circuit to 2 circuits(2)Increase evaporator width by 2 in.(3)by redesigning the unit’s user interface placement.Increase Baseline Chassis Size by: Width 3 in., Height 0.75 in., Depth 2 in.(4)Change Main Control Board to a Switching Power Supply.(5)Increase Baseline Chassis Size by: Width 4.19 in., Height 1.88 in., Depth 5.72 in. Convert Condenser and Evaporator to 3-tube row heat exchangers(6)and change Condenser to Plain FinIncrease tubing OD in condenser and evaporator from 5millimeter (mm)(7)to 7 mmReplace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor(8)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(9)5-D-10Table 5-D.3.2MarkN Results for 8000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class 3)Design Option StepMarkN FilenameCompressor Map(EER, Capacity)MarkN OutputsStand-byPowerIEEREERCapacityR-410A ConversionIn_PC3_12k_Baseline_R410A.dat9.39 EER 7.6 kBtu/h9.3076881.49.191 Increase Evap WidthIn_PC3_8k_Step1.dat9.39 EER 7.6 kBtu/h9.5479111.49.432 Increase Evap Tube ODIn_PC3_8k_Step2.dat9.39 EER 7.6 kBtu/h9.6980591.49.583 Add SubcoolerIn_PC3_8k_Step3.dat9.39 EER 7.6 kBtu/h9.7981001.49.684 Increase Chassis toMedium SizeIn_PC3_8k_Step4.dat9.39 EER 7.6 kBtu/h10.7086921.410.565 Stand-by ReductionIn_PC3_8k_Step5.dat9.39 EER 7.6 kBtu/h--0.710.636 Increase Chassis toLarge SizeIn_PC3_8k_Step6.dat9.39 EER 7.6 kBtu/h11.1289310.711.047 Increase PSCEfficiencyIn_PC3_8k_Step7.dat9.39 EER 7.6 kBtu/h11.7089370.711.628 DC Brushless MotorIn_PC3_8k_Step8.dat9.39 EER 7.6 kBtu/h11.9089390.711.81Increase evaporator width by 3 in.(1)by redesigning the unit’s user interface placementIncrease tubing OD in evaporator from 5 mm to 7 mm(2)Add subcooler with 0.25 in. OD, 24.25 in. length,(3)and condensate temperature of 95o FIncrease baseline chassis size by: Width 0.81 in., Height 3.13 in., Depth 2.5 in.(4)Change Main Control Board to a Switching Power Supply.(5)Increase baseline chassis size by: Width 4 in., Height 2.75 in., Depth 8.1 in.(6)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(7)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(8)5-D-11Table 5-D.3.3MarkN Results for 12000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class 3)Design Option StepMarkN FilenameCompressor Map(EER, Capacity)MarkN OutputsStand-byPowerIEEREERCapacityR-410A ConversionIn_PC3_12k_Baseline_R410A.dat9.14 EER 11.3 kBtu/h9.41123901.49.341 Add SubcoolerIn_PC3_12k_Step1.dat9.14 EER 11.3 kBtu/h9.58125061.49.512 Increase Chassis Size toMedium SizeIn_PC3_12k_Step2.dat9.28 EER 10.9 kBtu/h10.81120821.410.723 Standby ReductionIn_PC3_12k_Step3.dat9.28 EER 10.9 kBtu/h--0.710.764 Increase Chassis Size toLarge SizeIn_PC3_12k_Step4.dat9.28 EER 10.9 kBtu/h11.07123340.711.025 Increase Evap Tubes ODIn_PC3_12k_Step5.dat9.28 EER 10.9 kBtu/h11.14124550.711.096 Increase PSC EfficiencyIn_PC3_12k_Step6.dat9.28 EER 10.9 kBtu/h11.48124660.711.437 DC Brushless MotorIn_PC3_12k_Step7.dat9.28 EER 10.9 kBtu/h11.59124690.711.54Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F(1)Increase baseline chassis size by: Width 1 in., Height 2.5 in., Depth 0 in.(2)Change Main Control Board to a Switching Power Supply.(3)Increase baseline chassis size by: Width 2.75 in., Height 2.5 in., Depth 4.5 in.(4)Increase tubing OD in evaporator from 5 mm to 7 mm(5)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(6)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(7)5-D-12Table 5-D.3.4MarkN Results for 24000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Product Class 5)Design Option StepMarkN FilenameCompressor Map(EER, Capacity)MarkN OutputsStand-byPowerIEEREERCapacityHFC-22 BaselineIn_PC5_Baseline_R22.dat10.7 EER 24.1 kBtu/h8.50242861.48.47R-410A ConversionIn_PC5_Baseline_R410A.dat9.79 EER 24.1 kBtu/h7.87224771.47.841 Add SubcoolerIn_PC5_Step1.dat9.79 EER 24.1 kBtu/h8.17230071.48.142 Increase Chassis size toMedium SizeIn_PC5_Step2.dat10.0 EER 23.1 kBtu/h8.98229981.48.953 Increase Chassis size to LargesizeIn_PC5_Step3.dat10.0 EER 23.1 kBtu/h9.76243720.79.724 Standby IncreaseIn_PC5_Step4.dat10.0 EER 23.1 kBtu/h--0.79.745 Increase PSC EfficiencyIn_PC5_Step5.dat10.0 EER 23.1 kBtu/h10.06243940.710.046 Scroll CompressorIn_PC5_Step6.dat9.8 EER 20.0 kBtu/h10.55248440.710.537 DC Brushless MotorIn_PC5_Step7.dat9.8 EER 20.0 kBtu/h10.66248500.710.63Add subcooler with 0.282 in. OD, 63 in. length, and condensate temperature of 95o F(1)Increase baseline chassis size by: Width 1.75 in., Height 0.25 in., Depth 2.53 in.(2)Increase baseline chassis size by: Width 3.81 in., Height 4.69 in., Depth 2.53 in.(3)Change Main Control Board to a Switching Power Supply.(4)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(5)Replace Rotary Compressor with Scroll Compressor(6)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(7)5-D-13Table 5-D.3.5MarkN Results for 8000 Btu/h Non-Louvered, No Reverse Cycle Room Air Conditioner (Product Class 8)Design Option StepMarkN FilenameCompressor Map(EER, Capacity)MarkN OutputsStand-byPowerIEEREERCapacityR-410A ConversionIn_PC8_8k_Baseline_R410A.dat9.78 EER 7.2 kBtu/h8.4379681.48.341 Increase Evap WidthIn_PC8_8k_Step1.dat9.78 EER 7.2 kBtu/h9.4482751.49.342 Add SubcoolerIn_PC8_8k_Step2.dat9.78 EER 7.2 kBtu/h9.5983481.49.483 Stand byIn_PC8_8k_Step3.dat9.78 EER 7.2 kBtu/h--0.79.534 Increase PSC EfficiencyIn_PC8_8k_Step4.dat9.78 EER 7.2 kBtu/h10.0583560.79.995 Increase Evap Tubes ODIn_PC8_8k_Step5.dat9.78 EER 7.2 kBtu/h10.1785760.710.116 DC Brushless MotorIn_PC8_8k_Step6.dat9.78 EER 7.2 kBtu/h10.3385780.710.26Increase evaporator width by 4 in. by redesigning the uni(1)t’s user interface placement.Add subcooler with 0.25 in. OD, 24.25 in. length, and condensate temperature of 95o F(2)Change Main Control Board to a Switching Power Supply(3)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(4)Increase tubing OD in evaporator from 5 mm to 7 mm(5)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(6)5-D-14Table 5-D.3.6MarkN Results for 12000 Btu/h Non-Louvered, No Reverse Cycle Room Air Conditioner (Product Class 8)Design Option StepMarkN FilenameCompressor Map(EER, Capacity)MarkN OutputsStand-byPowerIEEREERCapacityR-410A ConversionIn_PC8_12k_Baseline_R410A.dat9.03 EER 11.5 kBtu/h8.37118691.48.321 Add SubcoolerIn_PC8_12k_Step1.dat9.03 EER 11.5 kBtu/h8.57120371.48.512 Increase Cond width w/ CoilBendIn_PC8_12k_Step2.dat9.03 EER 11.5 kBtu/h8.87122731.48.803 Increase Evap widthIn_PC8_12k_Step3.dat9.40 EER 11.1 kBtu/h9.35124421.49.284 Increase Evap Tube ODIn_PC8_12k_Step4.dat9.40 EER 11.1 kBtu/h9.55128861.49.485 Standby IncreaseIn_PC8_12k_Step5.dat9.40 EER 11.1 kBtu/h--0.79.516 Increase Cond Tube ODIn_PC8_12k_Step6.dat9.40 EER 11.1 kBtu/h9.68128200.79.647 Increase PSC EfficiencyIn_PC8_12k_Step7.dat9.40 EER 11.1 kBtu/h10.01128320.79.978 DC Brushless MotorIn_PC8_12k_Step8.dat9.40 EER 11.1 kBtu/h10.11128360.710.07Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F(1)Increase condenser width by 5 in. by bending the condenser coil to create more room.(2)Increase evaporator width by 6 in.(3)by redesigning the unit’s user interface placement.Increase Tubing OD in Evaporator from 5 mm to 7 mm(4)Change Main Control Board to a Switching Power Supply(5)Increase tubing OD in condenser from 5 mm to 7 mm(6)Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor.(7)Replace PSC Motor with an 80 percent efficiency Brushless DC Motor(8)5-D-15

# 5-D.4 DESCRIPTION OF SUPPORTING ANALYSES

This section presents additional description of two aspects of the engineering analysis for room

air conditioners:

Airflow modeling

Motor pricing analysis

5-D.4.1 Room Air Conditioner Airflow Modeling

Many factors influence the airflow characteristics of a room air conditioner. The flow

passages, heat exchangers, motor and fans all influence the airflow behavior within the room air

conditioner. The MarkN model treats the heat exchanger dimensions, airflows, and motor power

as separate, decoupled inputs, so the effect of physical changes in the airflow system on the

airflow and motor power must be calculated separately from the model. DOE conducted an

airflow calculation for each distinct airside design configuration.

DOE calculated the system airflow using an iterative approach with the following steps.

1. Select an airflow rate

2. Calculate fan or blower pressure rise

3. Calculate heat exchanger pressure drops using MarkN

4. Calculate other system pressure drops using spreadsheet calculation.

5. Add pressure drops and compare to fan or blower pressure rise.

a. If fan pressure rise is higher than total pressure drop, increase is airflow rate and

return to step 2

b. If fan pressure rise is lower than total pressure drop, reduce airflow rate and return

to step 2

c. If fan pressure rise and total pressure drop are equal within reasonable tolerance,

airflow calculation is complete.

The airflow modeling was based on calculating the pressure drops for the separate

components of the room air conditioner and the pressure rise associated with the condenser fan

or the evaporator blower. The approaches for calculating the pressure characteristics of the key

component are listed in Table 5-D.4.1 below.

5-D-16

# Table 5-D.4.1 Components Modeled to Calculate Room Air Conditioner Airflow

Component Pressure Drop Value or Calculation

Method Sources

Evaporator Blower Total Pressure Curve, adjusted using Fan

Laws to match observed baseline unit

performance. Comair Rotron Fan Company Ltd

2008 ASHRAE Handbook:

HVAC Systems and Equipment

Condenser Fan Static Pressure Curve, adjusted using Fan

Laws to match observed baseline unit

performance. Sofasco International

2008 ASHRAE Handbook:

HVAC Systems and Equipment

Filter 0.25 inches of water Filter vendors

Grilles and Louvers Loss coefficient times velocity pressure 2005 ASHRAE Handbook: Fundamentals

Ducts and Transitions Loss coefficient times velocity pressure 2005 ASHRAE Handbook: Fundamentals

Inflow to Condenser

(transition from fan

outlet to condenser) 50 percent of Condenser Pressure Drop Estimate

Heat Exchangers MarkN Outputs MarkN Model



# Fan performance curves provided a relationship between fan static pressure rise and

airflow delivered by the fan. DOE obtained fan performance curves for fans similar in size and

geometry to those used in the teardown units. The fan performance curves were adjusted as

needed to match the sizes, rotational speed, and performance of the modeled room air

conditioner fans using the fan laws.

On the evaporator side, DOE accounted for the airside pressure losses of the evaporator,

the entry and exit grilles, the filter, and the impeller exit transition. On the condenser side, DOE

accounted for the pressure losses of the condenser, the airflow path from the louvers to the fan

inlet, and the fan exit plenum geometry.

The evaporator and condenser pressure drops were calculated by the MarkN model based on

assumed airflow rate.

5-D.4.2 Room Air Conditioner Motor Analysis

Through examination of the teardown units and interviews with room air conditioner

manufacturers, DOE determined that PSC motors are the primary motor technology used in room

air conditioners to power the fan and blower assemblies. DOE examined improvement in motor

efficiency, including higher efficiency PSC motors and brushless DC motors as design options

for improving the energy-efficiency of the room air conditioners.

For all of the teardown units, DOE measured the power consumption of the motor at the

available fan speeds. In accordance with the current test procedure, DOE used the data for the

highest fan setting in its energy models, by using the energy consumption of each fan as a model

input. Changes in the technology of the fan motor from design options are expressed in the

model through changes in the fan motor energy consumption.

Figure 5-D.4.1 below shows the steps taken to develop the incremental costs for the PSC

motor efficiency increases. DOE researched motor characteristics and prices and established a

5-D-17

# room air conditioner motor database. DOE developed separate correlations for price and

efficiency as functions of motor weight and extended this analysis to develop a relationship for

incremental costs for increases in efficiency for PSC motors.

Figure 5-D.4.1 Motor Incremental Cost Steps

Teardown Unit Motor Sizes

The costs associated with increasing efficiency varied by motor shaft output rating. DOE

examined the motor shaft output ratings associated with each of the different product classes, and

used the baseline PSC shaft output rating as the basis of its efficiency analysis. Figure 5-D.4.2

shows the shaft output power of the motors that were examined during the reverse engineering

work, identified by product class and room air conditioner efficiency level (baseline or high).

Figure 5-D.4.2 Motor Shaft Output Ratings by Capacity for

Different Product Classes

5-D-18

# Motor Efficiencies

DOE obtained PSC motor efficiency data from discussions with motor vendors, review of

motor catalogs, and discussions with room air conditioner manufacturers. Most PSC motors

found in room air conditioners have a full-load efficiency between 45 percent and 60 percent.

High efficiency PSC motors can reach up to 70 percent efficiency. DOE selected an efficiency of

50 percent as the baseline for the room air conditioner PSC motors, and an efficiency of 70

percent for high efficiency PSC motors.

Cost as a Function of Weight

The DOE examined motor prices for a range of power ratings from a variety of motor

vendors. DOE examined the correlation of motor prices with weights, incoming electrical

current, incoming electrical voltage and shaft power for both single-shafted and double-shafted

HVAC PSC motors.

DOE noted that, across motors of similar shaft output, motor frame size, and voltage,

motor weight consistently increases as the efficiency increases. DOE found a strong correlation

between motor pricing and motor weight across all motor data, and used a subset of this data to

establish a basis for pricing PSC efficiency improvements. DOE established a statistically

significant correlation between motor price and motor weight using data from two motor

vendors, for motors with rated shaft output up to 0.25 horsepower (186.5 Watts (W)). Figure 5­

D.4.3 below shows the motor data used to establish this relationship.

The correlation establishes the increased cost of a motor per increase in weight, for PSC

motors within the range of established room air conditioner motors. It was established as

statistically significant through statistical t-tests and DOE used the ratio of cost per weight

increase to help calculate the cost of increasing the motor efficiency by a given amount.

5-D-19

# Figure 5-D.4.3 Motor Pricing Increase with Weight Increase

Efficiency as a Function of Weight

Available motor data did not generally included efficiency. However, full-load current

data was available for most motor entries. Current is an indicator of efficiency, assuming that

power factor does not change significantly among motors that are compared. The relationships

between current and motor weight for a range of applicable motor sizes is illustrated in Figure 5­

D.4.4 below. These relationships were developed from the available motor data.

5-D-20

# Figure 5-D.4.4 Weight-Current Curves for room air conditioner

PSC motors, grouped by shaft output

Cost as Function of Efficiency

DOE combined the cost/weight and the current/weight relationships to develop a

relationship for the cost of increasing motor efficiency from 50 percent to 70 percent as a

function of shaft output power. DOE determined the incremental cost for this efficiency increase

for the shaft output power levels of interest using the equation below.

The curve shown in Figure 5-D.4.5 below illustrates the resulting cost increase as a

function of shaft power. This relationship was developed for shaft power up to roughly 100W.

The high end of the relationship was extrapolated linearly to 200W to represent the cost of a high

efficiency PSC motor for a product class 5 product. DOE expects that the linear extrapolation is

conservative, since the curve’s slope decreases as shaft power increases.

5-D-21

# Figure 5-D.4.5 Cost of Increase d Efficiency for Differen t Motor

Output Ratings

Brushless DC Motors

BLDC motors are a more efficient alternative to PSC motors, and are already in use in

products such as in PTACs. BLDC motors provide the same output power as PSC motors at

higher efficiencies. DOE obtained BLDC motor efficiency data from discussions with motor

vendors, review of motor catalogs, and discussions with room air conditioner manufacturers.

Typical BLDC motors have efficiencies between 70 percent and 90 percent. However, in

searching for replacement motors for room air conditioners, DOE found that the average

efficiency of these motors is approximately 80 percent; motors with 90 percent efficiency are not

very common. DOE selected a BLDC motor efficiency of 80 percent for the analysis.

DOE searched motor catalogs and contacted motor vendors to develop a database of

BLDC motor characteristics. Using this data, DOE developed a representative relationship for

the cost premium of BLDC motors as a function of shaft power. This is shown in Figure 5-D.4.6.

5-D-22

# Figure 5-D.4.6 Brushless DC Motor Cost Curve by Shaft Output

Rating

5-D-23